It has been quite a while since I switched to using only Jabber (a.k.a. XMPP) for all my instant messaging. We use Jabber a lot at work, as well, and there are plans to set up an internal Jabber server eventually. (At the moment, everyone uses their personal Jabber IDs, which isn't ideal.)
I've been having problems with jabber.org.uk lately - they seem unreliable at times, although they're going through a complicated migration to ejabberd which should eventually fix things. In the meantime, because I rely on it so heavily, I need it to work now.
Also, I wanted a cooler Jabber ID, so I set up my own server. Hopefully, using ejabberd and being on a server with just one user will make things more stable.
So, as of now, you can add [email protected] to your contacts, the same as my email address. The old accounts will be going offline as soon as I've migrated everyone away.